Customs officers seized the consignment and paraphernalia required to manufacture up to 12m cigarettes from a 40ft-container, which had arrived via Holyhead into Dublin Port on Monday.
The load, which was declared as paper, showed up inconsistencies when profiled by officers and when scanned by the Customs X-ray scanner.
The consignment was followed to a premises in Co Monaghan where officers moved in and seized the illegal load.
Officers believe it was destined for a cigarette-making plant in the border area.
The investigation is ongoing nationally and internationally.
